Rainy weather due to multiple factors


First Posted: 6/11/2009

Persistent rainfall that has drenched this region for much of the spring is due to abnormal weather patterns that are expected to continue through late June, an expert says.
Although the massive precipitation has brought flooding and problems from thunderstorms, the good news is the area no longer is considered drought-stricken, according to Peter Corrigan of the National Weather Service.
Thats over, added Corrigan, who as a service hydrologist for the agencys Blacksburg, Va., office closely monitors conditions for Southwest Virginia and nine North Carolina counties including Surry. May pretty much put an end to that, Corrigan said Thursday of the drought.
Mount Airy received a whopping 8.08 inches of rain last month, almost double the average output for May of 4.12 percent, according to readings at the F.G. Doggett Water Plant, the citys official weather-monitoring station. Rain fell on 22 of the months 31 days, the most coming on May 27 when 2.01 inches were logged.
The total here was the second-highest for May since local weather records were first kept in 1924. The only May to surpass that was in 1950, when 9.52 inches were measured, according to research by water plant spokesman David Puckett. The all-time record for any month in Mount Airy is 13.37 inches in July 1964, Puckett said.
Some counties in the Blacksburg service region received as much as 10 or 12 inches last month, Corrigan said. May was one of the wettest months weve had in this area since this office was established in 1994, the hydrologist said.
It produced the most precipitation in the region during any single month since June 2006, a period marked by massive flooding, according to the National Weather Service spokesman.
As of May 31, Mount Airys annual precipitation level is 18 percent, or 3.38 inches, above normal.

Northern Fronts Stalled
Though May is over, the rainy pattern is continuing for June, due to the same meteorological forces remaining in place, Corrigan said. The main ingredient surrounds unusual movements of weather systems.
We have had a lot of frontal boundaries that have tended to come down from the north and stall out over the area, he explained. Weve had these fronts that sort of hang around.
Usually when we get into this time of year in this part of the country, the fronts dont even make it this far, said the National Weather Service spokesman, who pointed out that the systems normally stay in New England and other northern regions.
A hit-or-miss nature seen with that pattern in this region caused varying amounts of precipitation to be received during May, depending on ones location. Some places got a lot of rain and some didnt get so much, the hydrologist said.
Along with the stalling of the northern fronts over the area, other factors have played a role, Corrigan said. These have included the strong sun that occurs at this time of year and stiff upper-level winds that have energized higher realms of the atmosphere and caused intense thunderstorms in some cases.
This pattern has persisted since the first few days of June, Corrigan added of the prevailing weather conditions.
As of Thursday morning, 2.68 inches of rainfall already had been measured in Mount Airy so far in June. We just received another eight-tenths, a spokesman at the water plant said early Thursday afternoon, which pushed the total for the month to 3.48 inches.
The same weather trend is expected to continue through June 25, the farthest into the future that Corrigan could predict as of Thursday. Its got us wetter than normal, he said of the profile for that period.
Typically in late June and July, the northern fronts no longer will be showing up in this area, and drier conditions should prevail, although Corrigan does not expect a reoccurrence of drought.
The hydrologist explained that the La Nina pattern that has brought unusually cold temperatures to the Pacific Ocean, and coincided with drought conditions in the Southeast in recent years, is no longer in effect. This region is now in a neutral pattern where the Pacific influences are concerned, Corrigan said.
Contact Tom Joyce at [email protected] or at 719-1924.

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